import itertools

n, k = map(int, input().split())
A = list(map(int, input().split()))
A.sort()
B = []
for k, g in itertools.groupby(A):
    B.append(len(list(g)))
B.sort()

cnt = 0
while k > 0:
    cnt += 1
    k -= B.pop()

print(cnt)